Pseudomonas aeruginosa is a Gram negative bacterium which poses a serious threat to immunocompromised patients as well as those with cystic fibrosis. Resistance of this bacterial pathogen to antibiotics is the main cause of therapeutic failure. B-lactams are important anti-pseudomonas antibiotics and bacterial resistance to this class of antibiotics involves multiple mechanisms, but occurs primarily through overexpression of class C ?-lactamase (AmpC), which is insensitive to ?-lactamase inhibitors currently used in clinic. We have recently identified and characterized the ampG gene in this bacterium, which encodes a membrane transporter involved in cell wall recycling and is essential for the ampC expression. Interestingly, P. aeruginosa with ampG mutation is much more sensitive to ?-lactams than the ampC mutant, indicating that the AmpG is required for multiple mechanisms of ?-lactam resistance. Consistent with this, sensitivity to ?-lactams can be restored among pan-?-lactam resistant clinical isolates of P. aeruginosa by knocking out their ampG genes, demonstrating AmpG is an ideal target for the control of resistance. In this proposal, we intend to elucidate the molecular mechanisms of AmpG-dependent resistance against ?-lactams and identify effective AmpG inhibitors for clinical application. As cell wall recycling is a common process among Gram Negative bacteria, the AmpG inhibitors will be effective against broad spectrum of bacteria. Effective AmpG inhibitors can help us to fight against ?-lactam resistant pathogens while bring ineffective ?-lactams to life, expanding our arsenals against the deadly bacterial infections.